he most common etchants for heat treated steels or martensitic microstructures contain picric acid dissolved in alcohol and acids. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies, http://www.metallographic.com/Consumables/Etch.htm
Sample Preparation: Both heat treated and un-heat treated steels must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:
http://www.metallographic.com/Procedures/Steel%20Description.htm
http://www.metallographic.com/Brochures/Met-Manual-2b.pdf
CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers SDS (Safety Data Sheets). Also review COMMENTS Section for each etchant.
| Etchant | Conc. | Conditions | Comments |
| Picral Ethanol Picric acid |
100 ml 2-4 grams |
Seconds to minutes | For heat treated steels Do not let etchant dry-explosive |
| Ethanol Nitric acid Hydrochloric acid Picric acid |
80 ml 10 ml 10 ml 1 gram |
Seconds to minutes | Grain boundaries |
| Nital Ethanol Nitric acid |
100 ml 1-10 ml |
Seconds to minutes | Do not exceed 10% nitric acid -explosive |